1. Field of the Invention
This invention relates to a high speed, microcomputer based, Fibre Channel compatible and fault tolerant information processing and mass storage system especially suited for information servers and application servers. In particular, the present invention relates to a method and apparatus for information processing and storage involving a unique and extremely versatile system architecture, including a dual loop arbitrated, Fibre Channel capable, multiple-fault tolerant, hot-swappable mass storage disk array and including a method and apparatus for providing an enterprise-wide information or application server system using such disk array.
2. State of the Art
Efforts have been made in the past to provide a mass storage file server capable of delivering information throughout an enterprise with high speed data throughput, scalable data storage capability in a convenient, easily configurable enclosure using well known, industry standard operating software and hardware. However, such systems have typically experienced many shortcomings and problems associated with equipment incompatibility as well as with the inability of presently available computer and communications hardware to sustain performance and service failure of component devices. Such shortcomings have included the lack of capability to add storage devices to accommodate increased storage requirements or to replace failed storage devices without the need to completely power down the information server. Some of the compatibility problems have involved, for example, bottlenecks in sharing information among the equipment components of various vendors. The above-referenced Dellacona patent applications address some of these problems and others, and provide unique solutions which are described and claimed therein.
The present invention further addresses some of the problems discussed in the referenced Dellacona applications, as well as others. For example, the present invention further addresses the problem of scalability and customization in information processing and storage systems for different applications. In some applications, there may be a greater need for processing capability rather than storage capacity, while other applications may require just the opposite. Yet other applications may require storage expansion for existing information processing systems. This invention provides an architecture which will readily accommodate such needs.
In addition, mass storage systems can create considerable heat, particularly where they are disk drive based. If the heat is not effectively removed, it can affect the reliability and life of the system. Often, it is difficult to remove the heat because of obstructions caused by the physical configuration of back planes and mid planes which act as barriers to air flow. Typically, for example, all of the disk drives of a mass storage module or array are typically plugged into connectors on the face of a backplane or mid plane that extends across the entire module. Whether enclosed in a cabinet or other enclosure or rack mounted without an enclosure, air flow through the module is inhibited by this type of structural arrangement, and excessive heating can occur, particularly in the vicinity of the disk drives.
Also, it is desirable to be able to hot swap individual disk drives of a mass storage module to accommodate the need for more storage capacity, but the system storage requirements may outgrow the capacity of the module and it may also be desirable to have the capability of adding modules without powering down the system. Of course, this capability must be provided without disturbing the operation of the existing module and with a minimum of signal degradation as modules are added.